Cigarette ventilation achieved with coated wrapper

ABSTRACT

A cigarette or smoking article is provided with ventilation or smoke dilution character by employing a wrapper which normally is sufficiently air-pervious to admit significant dilution air stream flow therethrough when the cigarette is puffed. The wrapper is coated on either of its inner or outer surface with an air-impervious material which is degradable in the presence of tobacco smoke, and a coating of a second air-impervious material which is non-degradable in the presence of smoke is embodied in the cigarette and extends a predetermined distance from the cigarette smoking end toward the mouth end to prohibit entry of air stream flow through the wrapper until the cigarette has been smoked said predetermined distance following which the degradable coating on the remaining length degrades to admit such air stream flow.

United States Patent Stewart, Jr. et al.

[ 1 Apr, 23, 1974 CIGARETTE VENTILATION ACHIEVED WITH COATED WRAPPERFiled:

Appl. No.: 272,321

Inventors: Lawrence L. Stewart, Jr.; Homer A.

Hartung, both of Richmond, Va.

Assigneez, Philip Morris Incorporated, New

York, N.Y.

July 17, 1972 US. Cl. 131/9, 131/10 A, 131/15 B Int. Cl A24d 01/02 Fieldof Search 131/4 A, 15 R, 15 B, 8 R,

References Cited UNITED STATES PATENTS 7/1961 Figge 131/15 BX 6/1972Sanford et al. 131/15 B 5/1956 Legler 131/15 RX 8/1968 Kahane 131/8 R XPrimary ExaminerRobert W. Michell Assistant Examiner-John F. Pitrelli[57] ABSTRACT A cigarette .or smoking article is provided withventilation or smoke dilution character by employing a wrapper whichnormally is sufficiently air-pervious to admit significant dilution airstream flow therethrough when the cigarette is puffed. The wrapper iscoated on either of its inner or outer surface with an airimperviousmaterial which is degradable in the presence of tobacco smoke, and acoating of a second airimpervious material which is non-degradable inthe presence of smoke is embodied in the cigarette and extends apredetermined distance from the cigarette smoking end toward, the mouthend to prohibit entry of air stream flow through the wrapper until thecigarette has been smoked said predetermined distance following whichthe degradable coating on the remaining length degrades to admit suchair stream flow.

15 Claims, 8 Drawing Figures CIGARETTE VENTILATION ACHIEVED WITH COATEDWRAPPER BACKGROUND OF THE INVENTION Cigarette ventilation as a means ofcontrolling cigarette TPM delivery profile is known. For example, holescan be'provided in cigarette wrapper to admit air to dilute the smoke ofthe cigarette and thus reduce the delivery of each puff. U.S. Pat. No.2,992,647 teaches that a covering of heat degradable material over theholes would provide means to give ventilation progressing with theadvance of the burning coal, so that the ventilation would not decreaseas the cigarette was smoked. U.S. Pat. Nos. 3,526,904 and 3,511,247disclose improved means to accomplish this progressive opening. Thedelivery puff-by-puff, which taken as a whole is referred to as theprofile, thus can be controlled so that there is less difference betweenthe low TPM level early puffs and the higher TPM later ones; at the sametime the total overall TPM delivery is less than for an unventilatedcigarette. Cigarettes produced according to the aforementioned patentswhile quite effective for the intended purpose have certain drawbacksprincipally in respect of the difficulties associated with producingcoated wrappers as prescribed on high speed machinery at economicproduction rates.

SUMMARY OF- THE INVENTION The present invention is concerned with asimplified manner of accomplishing leveling of the TPM delivery profileof a cigarette by ventilation wherein a smoke degradable materialcoating is degraded by tobacco smoke to admit significant dilution airstream flow through the wrapper to the cigarette. The cigarette wrapperis made exceptionally porous, either by its physical composition andstructure or by virtue of perforations made in it and is coated on theouter or inner side with a thin layer of material which is stable underconditions of manufacture and storage, which material further issubstantially impervious to air flow, but is degraded by concentratedto'baccosmoke. This material can be of the type disclosed in the abovementioned U.S. patents. The wrapper is further coated on the inside oroutside, in a selected area, with a thin layer of a second similarlystable and impervious material, but which is not degradable byconcentrated smoke. The area of the paper coated with the secondmaterial is located at and adjacent to the end of the cigarette furthestfrom the smoker, that. is, the smoking end. The portion of the cigaretteso covered will deliver undiluted smoke during the early puffs since aircannot pass through the wrapper; as the smoke degrades the layer whichcoats that portion not covered by the second material, the porous paperwill be uncovered to admit air and the later puffs will be diluted tocounteract the trend toward higher TPM delivery. The pattern of coverage of the second material may be a simple one ending at acircumferential line, or it may be serrated to provide a gradualtransition from non-ventilated to ventilated smoking condition. Thenon-degradable covering may be superimposed over a selected portion ofthe coating of degradable materials which has been previously applied,or the two materials may be applied exclusively of each other toseparate areas of the paper.

It is also possible to apply either or both material coatingsdiscontinuously to the wrapper, in such man ner that some uncoated areasremain therein, so that from the beginning of smoking a. positive butlimited amount of dilution air flow can occur through the wrapper. Thisflow then is supplemented to give the required increasing ventilation asthe degradable coating begins to be attacked. In such form, the coatingsmay be applied in separated longitudinal strips, or for zero porositypaper continuously except for one or two uncoated stripes, totalling 0.5to 10 percent of the wrapper area.

The non-degradable material can be any suitable material which isnon-degradable in the presence of smoke and which is otherwise stable atdistances of about 3 mm and more beyond the burning coal of thecigarette. Particularly suited for this purpose are cellulose acetateand polystyrene.

The invention accordingly comprises the features of construction,combination of elements, and arrangement of parts, which will beexemplified in the construction hereinafter set forth and the scope ofthe invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS A fuller understanding of the natureand objects of the invention will be had from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is alongitudinal vertical sectional view of a ventilatedcigarette made in accordance with the principles of the presentinvention, the smoke degradable coating being on the inner surface ofthe tobacco cylinder wrapper extending the full length thereof, and thenon-degradable coating being on the outer surface of the wrapperextending from the smoking end a predetermined distance only in thedirection of the mouth end.

FIG. 2 is a view similar to FIG. I except that the degradable coating ison the wrapper inner surface extending the full length thereof with thenon-degradable coating being laid on the former. V

FIG. 3 is a view similar to FIGS. 1 and 2 except that both thedegradable and non-degradable coatings are on the wrapper inner surfaceextending only predetermined lengths in the wrapper to a common juncturecloser to the smoking end than the mouth end of the cigarette. e

FIG. 4 is a perspective view of a ventilated cigarette in which thedegradable coating is on the wrapper inner surface extending the fulllength thereof and the nondegradable coating is on the outer surface,the latter including serrated segments remote from the cigarette smokingrend to provide for a progressive transition from non-ventilated toventilated smoking condition.

FIG. 5 is a perspective view of the cigarette shown in FIG. 4 beingprovided additionally with a filter element at the smoking end thereof.

FIG. 6 is a perspective view of a ventilated cigarette embodying afurther form of materials coating arrangement in which certain areas ofthe wrapper inner and outer surfaces are left uncoated to provide apositive but limited dilution air inflow at all times during the courseof smoking of the cigarette.

FIG. 7 is a side elevational view on enlarged scale partly in section ofa cylinder embodying still a further form of pattern in which thematerials coatings can be applied to a cigarette wrapper.

FIG. 8 is a graph illustrating the TPM delivery profile of cigarettesmade in accordance with the present invention and having in one form adegradable coating only, and in another form, both a degradable coatingand a non-degradable coating.

Throughout the following description like reference numerals are used todenote like parts in the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1 of thedrawings there is depicted a cigarette 10 made in accordance with thepresent invention, the cigarette including a cylinder of tobacco l2 anda wrapper l4 closely encircling the tobacco cylinder, the wrapper havinginner and outer surfaces. Wrapper 14 is an air-pervious componentprovided either as a very porous air-pervious paper or an anair-impervious paper which has been perforated with openings such as at16 to provide an air-pervious character thereto. In accordance with thepresent invention, the inner surface of wrapper 14 is coated with alayer 18 of a first air-impervious material which extends from one endof the wrapper in the direction of the other end, in the depictedembodiment such layer 18 extends the full length of the wrapper. Thematerial in layer 18 additionally is degradable in the presence oftobacco smoke. Materials suited to that purpose include the types ofmaterials disclosed in U.S. Pat. Nos. 2,992,647, 3,511,247 and3,526,904. A particularly suitable material is a low molecular weightpolyethylene oxide containing a peroxide, the peroxide functioning topartly degrade the coating subsequent to application to facilitate latercomplete degradation by tobacco smoke during smoking.

Wrapper 14 also is provided on the outer surface thereof with a layer orcoating 20 of a second airimpervious material which extends from thesmoking end of the cigarette a predetermined distance only in thedirection of the mouth end. The material in layer 20 is furthercharacterized by being non-degradable in the presence of tobacco smoke.Such material of course is consumable in the course of smoking, e.g., bythe action of the burning coal causing disintegration of the same.

As taught in U.S.'Pat. No. 2,992,647, there is a sharp temperaturegradient behind the coal of a cigarette. Substances which melt at 316Cremain stable beyond I mm behind the coal, while those that melt at 260Cmelt only at distances of2 to 3 mm behind the coal. Accordingly, it iswithin the contemplation of the present invention that any materialwhich is stable beyond 3 mm behind the coal can be employed as anondegradable coating provided it is not materially degradable bytobacco smoke. Among the film forming materials which are suitable forlayer 20 are cellulose acetate, other cellulose esters, polyoxyethylenewith a molecular weight above 1,000,000, high-melting polyethylene,polypropylene and polystyrene. To be useful of course these materialsmust be formed into a nonporous film. Placing the non-degradable coating20 outside of the degradable coating 18 as shown in FIG. 1, gives someprotection to the former in that it is shielded by the inner coatingfrom the smoke action and heat. While the inner coating l8-isdisintegrating it is protecting the outer coating 20 by absorbing heatenergy in the melting or decomposition process. Thus materials whichmight not by themselves resist tobacco smoke as long as is required forthe non-degradable film may serve the intended purpose.

When the cigarette 10 is smoked, initially the coating 20 will consumedue to the action of the burning coal but will not degrade in advance ofthe coal at distances beyond about 3 mm so that the coating 10 willremain intact to prohibit air stream entry to the tobacco cylinderthrough wrapper openings 16 at least until the cigarette has been smokedthe predetermined distance represented by the length of coating 20notwithstanding that the coating 18 has over such distance beendegraded. However once such coating 20 has been consumed, the coating 18being degraded by the tobacco smoke allows for such dilution air streaminflow to the cigarette.

The cigarettes 30 and 40 shown in FIGS. 2 and 3 respectively are quitesimilar to that shown in FIG. 1. Accordingly, the same referencenumerals where applicable are used and where components are differentthese are designated by prime and double prime reference numerals,respectively. Thus the non-degradable coating 20 of cigarette 30 insteadof being on the outer surface of wrapper 14 is inside the wrapper and islaid over the degradable coating 18. In FIG. 3, the degradable coating18" instead of extending the full length of the wrapper terminates incommon location with the nondegradable coating 20" both being at theinner surface of the wrapper.

FIG. 4 shows a further modified form of cigarette 60 which includes acylinder of tobacco 62 enclosed by wrapper 64, the latter being providedwith openings 66 and having on its inner surface a coating 68 of a smokedegradable material. A layer 72 of non-degradable material is coated onthe outer wrapper surface at the smoking end like in the cigarette 10,the layer 72 following a fully encircling course in respect of saidwrapper and having segments 74 which terminate as a plurality ofserration likeextensions to provide in cooperation with the coating 68 aregion of gradual transition in the wrapper from non-degradable airstream flow prohibition to degradable air stream flow admission.-Cigarette 60 is a non-filter type cigarette, and accordingly it may bedesirable to incorporate means to denote to the smoker the mouth endthereof. Accordingly, an indicia 76, e.g., a printed designation, can bemarked on the wrapper for that purpose.

The cigarette depicted in FIG. 5 is in all respects the same as thecigarette 60 shown in FIG. 4 and includes identical components, except,it includes a conventional smoke filter element 82 such as a wrappedcellulose acetate plug 84 joined to the cylinder of tobacco.

FIG. 6 depicts another form of cigarette in which the materials coatingsapplied to the wrapper 102 of cigarette are of a discontinuous orinterrupted nature so that a portion at least of the area of the wrapperremains uncoated. In this manner, a limited amount of dilution air flowcan occur through the wrapper from the very start of smoking of thecigarette. Preferably, both the degradable and non-degradable coatingsare applied in narrow bands extending longitudinally of the wrapper.Thus, the bands 104 of non-degradable material can be convenientlyapplied to the outer surface of the wrapper 102, whereas the degradablecoating bands 106 conveniently can be applied at the inner surface ofthe wrapper. As smoking of the cigarette progresses, there will beinitially supplied dilution air through openings 108 at the smoking endofthe cigarette which dilution air flow will be supplemented later inthe course of smoking when the degradable coating 106 uncovers theopenings 1 to increase the measure of dilution.

FIG. 7 shows a still further form of cigarette in which so-called zeroporosity paper is used for the wrapper. Zero porosity paper isunderstood by those skilled in the art as being a type of paper in whichthere is no time delay attending the passage of air flow through thepaper. Conventional cigarette paper while porous has some time delay andaccordingly would have a higher value in the grenier scale to indicatethat condition. In the cigarette 120 depicted in FIG. 7, the cigarettewrapper 122 of very high or zero porosity paper is coated on its outersurface with degradable polyethylene oxide except for a 0.2 mm widecontinuous longitudinal area extending end to end of the wrapper that isleft uncoated as at 126. The purpose of the latter is to maintain theinitial dilution that can be obtained in ordinary cigarettes by use ofmoderately porous paper.

The cigarette wrapper 122 is then overcoated with a non-degradablecoating, cellulose acetate in the pattern 124 so that dilution due toporosity of the wrapper is essentially the same as a normal cigarette atthe first puff and increases with succeeding puffs as larger areas ofdegradable coating are opened up by the smoke. The pattern is designedto limit the area of degradable coating within reach of degradingconditions for the first puffs, by applying non-degradable coating tothe first 6 mm measured from the smoking end 128. On the first andsecond puffs the dilution through the wrapper is the same as that of anormal cigarette and on succeeding puffs becomes progressively greaterthan in a normal cigarette to the extent that after the second puff, perpuff delivery is limited to approximately that of the second puff.

The invention will be understood further by-reference to the followingexamples.

EXAMPLE I Cigarette paper wrapper of very high porosity (zero grenier)but without any openings was coated with a solution of Polyox N-SOpolyoxyethylene (Union Carbide) containing benzoyl peroxide (5% of theresin weight) to give an overall coating of3 to 5 g/sq. m. Cigaretteswere made with this paper using a conventional tobacco filler.Additionally, conventional acetate filter plugs were attached (CigaretteA). Then some of these cigarettes were coated by hand with a solution ofcellulose acetate in acetone according to the pattern of FIG. 1, thecellulose acetate forming a non-degradable coating (Cigarette B). Whenthese cigarettes were smoked by machine according to the standard method(Wartman, Cogbill and Harlow, Analytical Chemistry 3l, 1705-11709(1958)) they gave significantly lower deliveries of particulate matterthan did a cigarette (Cigarette C) with the same components but withconventional paper wrapper. FIG. 8 shows the comparative profiles of TPMversus puff number for these cigarettes. The ratio of last-to-first puffdeliveries were about 6.7 for Cigarette A and about 3.0 for Cigarette B,such ratio being only about 2.0 for Cigarette C, but such ratio being aproduct of the expected significantly higher TPM delivery associatedwith a non-ventilated cigarette.

EXAMPLE 2 Cigarette paper of high porosity and coated with P0 lyoxpolyethylene oxide, as used in Example 1, was used to make conventionalcigarettes with acetate filter plugs. Then some of these cigarettes werecoated by hand with a solution of polystyrene dissolved in benzeneaccording to the pattern of FIG. 1, the polystyrene forming thenon-degradable coating. When these cigarettes were smoked according tothe standard method, as cited in Example 1, they gave significantlylower tar deliveries compared to cigarettes made with the same tobaccoand filter but with ordinary paper. The ratio of the last puff to firstpuff deliveries was about 3.2 to 1.

What is claimed is:

1. A smoking article comprising an elongated cylinder of tobacco, and

an air-pervious paper wrapper closely encircling said cylinder oftobacco, and having inner and outer surfaces, said wrapper normallybeing sufficiently air-pervious to admit air stream flow therethroughinto said cylinder of tobacco when said smoking article is puffed, saidarticle having a mouth end and a smoking end a coating of a firstair-impervious material disposed in a substantially fully encirclingcourse on one of said wrapper surfaces and extending for a substantiallength from the mouth end. of said article in the direction of thesmoking end, said first airimpervious material being characterized bybeing degraded by concentrated tobacco smoke during smoking of saidarticle to dissipate said first material coating thereby to permit.entry of air stream flow through said wrapper, and

a coating of second air-impervious material embodied with said smokingarticle and extending from a location at said smoking end of saidarticle a predetermined distance in the direction of the mouth endthereof, said second air-impervious material being characterized bybeingconsumable by the action of the burning coal during smoking but notdegradable in the presence of concentrated tobacco smoke thereby toprohibit entry of air stream flow through at least portions of saidwrapper at least until said smoking article has been smoked saidpredetermined distance.

2. The smoking articleof claim 1 wherein said coating of firstair-impervious material is on one of said wrapper surfaces, the coatingof second air-impervious material being on the other of said wrappersurfaces.

3. The smoking article of claim 1 wherein said coating of firstair-impervious material is on one of said wrapper surfaces and extendsthe full length of said one surface.

4. The smoking article of claim 3 wherein the coating of secondair-impervious material is on said coating of first air-imperviousmaterial.

5. The smoking article of claim 1 wherein said coating of secondair-impervious material is on one of said wrapper surfaces extendingsaid predetermined length on said one surface, the coating of firstair-impervious material being on the remaining, length of said onewrapper surface.

6. The smoking article of claim 1 wherein said paper wrapper is anair-impervious paper and is provided with apertures extendingtherethrough to render said wrapper air-pervious.

7. The smoking article of claim 1 wherein said coating of secondair-impervious material is embodied along the major portion of itslength in a fully encircling course in respect of said wrapper and hassegments thereof remote from said smoking end of said article providedas a plurality of serration-like extensions of said major portion, saidfirst coating extending in a course intermediate and adjacent saidserrations to provide therewith a region of gradual transition in saidwrapper from non-degradable air stream flow prohibition to degradablecoating air stream flow admission condition during the course of smokingsaid article.

8. The smoking article of claim 7 wherein said wrapper further includesa longitudinal extending area therein characterized by the absence ofnondegradable and degradable coating thereon.

13. The smoking article of claim 1 wherein said second air-imperviousmaterial is polystyrene.

14. The smoking article of claim 1 wherein said article is a cigaretteand said wrapper is provided with indicia denoting the smoking end ofsaid cigarette.

15. The smoking article of claim 1 wherein said smoking article is acigarette and further comprises a filter component joined to saidcylinder of tobacco at said mouth end of said article.

2. The smoking article of claim 1 wherein said coating of firstair-impervious material is on one of said wrapper surfaces, the coatingof second air-impervious material being on the other of said wrappersurfaces.
 3. The smoking article of claim 1 wherein said coating offirst air-impervious material is on one of said wrapper surfaces andextends the full length of said one surface.
 4. The smoking article ofclaim 3 wherein the coating of second air-impervious material is on saidcoating of first air-impervious material.
 5. The smoking article ofclaim 1 wherein said coating of second air-impervious material is on oneof said wrapper surfaces extending said predetermined length on said onesurface, the coating of first air-impervious material being on theremaining length of said one wrapper surface.
 6. The smoking article ofclaim 1 wherein said paper wrapper is an air-impervious paper and isprovided with apertures extending therethrough to render said wrapperair-pervious.
 7. The smoking article of claim 1 wherein said coating ofsecond air-impervious material is embodied along the major portion ofits length in a fully encircling course in respect of said wrapper andhas segments thereof remote from said smoking end of said articleprovided as a plurality of serration-like extensions of said majorportion, said first coating extending in a course intermediate andadjacent said serrations to provide therewith a region of gradualtransition in said wrapper from non-degradable air stream flowprohibition to degradable coating air stream flow admission conditionduring the course of smoking said article.
 8. The smoking article ofclaim 7 wherein said wrapper further includes a longitudinal extendingarea therein characterized by the absence of non-degradable anddegradable coating thereon.
 9. The smoking article of claim 1 whereinsaid first air-impervious material is a polyoxyethylene containing aperoxide.
 10. The smoking article of claim 9 wherein the peroxide ispresent in up to about 5% of the weight of said first air-imperviousmaterial.
 11. The smoking article of claim 10 wherein the peroxide isbenzoyl peroxide.
 12. The smoking article of claim 1 wherein said secondair-impervious material is cellulose acetate.
 13. The smoking article ofclaim 1 wherein said second air-impervious material is polystyrene. 14.The smoking article of claim 1 wherein said article is a cigarette andsaid wrapper is provided with indicia denoting the smoking end of saidcigarette.
 15. The smoking article of claim 1 wherein said smokingarticle is a cigarette and further comprises a filter component joinedto said cylinder of tobacco at said mouth end of said article.